Extrusion devices are used to melt, blend, and form materials, such as plastics, into a desired shape. Typical extrusion devices include a rotating screw housed coaxially within a heated, cylindrically-shaped feed throat and barrel. A portion of the feed throat is cut away forming an opening for admission of materials. A hopper is coupled to the extrusion device for feeding the material through the opening, into the feed throat and subsequently into the barrel. The screw rotates within the feed throat and barrel and drives the material therethrough. The extrusion material is forced through a die or aperture at a discharge end of the barrel.
Rotation of the screw within the feed throat typically involves a predetermined small gap between exterior portions of the screw and interior surfaces of the feed throat. The gap is sized to force the material to travel along the screw into the barrel. The interior surface can wear and cause the gap to become excessive. As a result, an unacceptable amount of material becomes stagnated in the feed throat.